JP2709405B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photosensitive member,
The present invention relates to an electrophotographic photosensitive member having excellent moisture resistance and durability.

(Prior Art) An electrophotographic photosensitive member has various configurations in order to obtain predetermined characteristics or according to the type of an applied electrophotographic process.

Representative electrophotographic photoreceptors include a photoreceptor having a photoconductive layer formed on a support and a photoreceptor having an insulating layer on the surface, and are widely used. A photoreceptor composed of a support and at least one photoconductive layer is used for image formation by the most common electrophotographic processes, ie, charging, image exposure and development, and, if necessary, transfer.

Further, a method using an electrophotographic photosensitive member as an offset master for direct plate making has been widely used.

The binder used to form the photoconductive layer of the electrophotographic photoreceptor has excellent film forming properties of itself and the ability to disperse the photoconductive powder in the binder, as well as the base of the formed recording material layer. It has good adhesion to materials, and the photoconductive layer of the recording layer has excellent charging ability, low dark decay, large light decay, low pre-exposure fatigue, and these characteristics due to changes in humidity during imaging. It is necessary to have various electrostatic characteristics, such as a need to stably hold, and excellent imaging properties.

As long-known resins, for example, silicone resins (Japanese Patent Publication No. 34-6670), styrene-butadiene resins (Japanese Patent Publication No. 35-1960), alkyd resins, array acid resins,
Polyamide (JP-B-35-11219), vinyl acetate resin (JP-B-41-2425), vinyl acetate copolymer (JP-B-41
No. 2426), an acrylic resin (Japanese Patent Publication No. 35-11216), and an acrylate copolymer (for example, Japanese Patent Publication No. 35-11219).
Nos. JP-B-36-8510, JP-B-41-13946, etc.) are known.

However, in the electrophotographic photosensitive material using these resins, 1) the affinity with the photoconductive powder is insufficient, and the dispersibility of the coating liquid is poor. 2) The chargeability of the photoconductive layer is poor. Low,
3) Poor quality of the image portion (particularly halftone dot reproducibility / resolution) of the copied image 4) The image quality is easily affected by the environment (for example, high temperature, high humidity, low temperature, low humidity) at the time of creating the copied image 5) Photosensitive layer However, when used as an offset master, there is a problem that the photosensitive layer is detached during offset printing and the number of printed sheets cannot be increased.

Various methods have been proposed as methods for improving the electrostatic properties of the photoconductive layer. One of the methods is, for example, a compound containing a carboxyl group or a nitro group in an aromatic ring or a furan ring, or an anhydride of a dicarboxylic acid. And JP-B-42-6878 and JP-B-45-3073. However, even the photosensitive materials improved by these methods do not have sufficient electrostatic characteristics, and no material having particularly excellent light attenuation characteristics has been obtained. Therefore, in order to improve the sensitivity shortage of this photosensitive material,
Conventionally, a method of adding a large amount of a sensitizing dye into the photoconductive layer has been adopted.However, the light-sensitive material produced by such a method significantly deteriorates whiteness and causes deterioration in quality as a recording medium. Causes deterioration of the dark decay of the photosensitive material,
There was a problem that a sufficient copied image could not be obtained.

On the other hand, Japanese Patent Application Laid-Open No. 60-10254 discloses a method in which the average molecular weight of the resin is adjusted and used as the binder resin used in the photoconductive layer. That is, by using an acrylic resin having an acid value of 4 to 50 and a component having an average molecular weight of 10 ³ to 10 ⁴ and a component having a distribution of 10 ⁴ to 2 × 10 ⁵ , the electrostatic properties (particularly,
A technique for improving the reproducibility of the PPC photoreceptor and the moisture resistance is described.

Furthermore, research on a lithographic printing original plate using an electrophotographic photoreceptor has been earnestly conducted, and a binder resin for a photoconductive layer having both electrostatic characteristics as an electrophotographic photoreceptor and printing characteristics as a printing original plate. For example, in Japanese Patent Publication No. 50-31011,
Fuar acid was under the presence (meth) copolymerized with acrylate monomers and other monomers, in ^{Mw1.8 × 10 4 ~10 × 10 4} Tg1
A resin in which a resin at 0 to 80 ° C. is used in combination with a copolymer comprising a (meth) acrylate monomer and a monomer other than fumaric acid, and JP-A-53-54027 discloses a method in which a carboxylic acid group is ester-bonded. Using a terpolymer containing a (meth) acrylic ester having a substituent having at least 7 atoms away from a tertiary copolymer, and JP-A-54-20735 and JP-A-57
JP-A-202544 uses a quaternary or pentameric copolymer containing acrylic acid and hydroxyethyl (meth) acrylate, and JP-A-58-68046 discloses an alkyl group having 6 to 12 carbon atoms as a substituent. The use of a terpolymer containing a (meth) acrylic acid ester and a carboxylic acid-containing vinyl monomer is effective in improving the desensitizing property of the photoconductive layer. However, even if the above-mentioned resin is said to be effective in electrostatic properties, moisture resistance properties and durability,
When actually evaluated, there are problems in particular, such as chargeability, dark charge retention, electrostatic properties such as photosensitivity, smoothness of the photoconductive layer,
It was not practically satisfactory.

Also, a binder resin developed as an electrophotographic lithographic printing plate precursor has a problem in the above-mentioned electrostatic characteristics, background contamination of printed matter, etc. when actually evaluated.

Further, in order to solve these problems, a copolymer component containing an acidic group in a side chain of the polymer as a binder resin is added in an amount of 0.05%.
The use of 10% by weight content to the low molecular weight resin (MW10 ³ to 10 ^4), the smoothness and electrostatic characteristics of the photoconductive layer was good, yet be obtained without background fouling quality JP 63 −
No. 217,354, further such a low molecular weight resin by the use in combination with the high molecular weight of the resin (MW10 ⁴ or higher), to improve the adequate and tighten printing durability film strength of the photoconductive layer without inhibiting the characteristics Japanese Patent Application No. 63-49817, Japanese Patent Application No. 63-22014
No. 8 and No. 63-220149.

(Problems to be Solved by the Invention) However, even if these resins are used, it is still insufficient to maintain stable performance when the environment fluctuates remarkably from high temperature and high humidity to low temperature and low humidity. Was. In particular, in the scanning exposure method using a semiconductor laser beam, the exposure time is longer and the exposure intensity is limited as compared with the conventional simultaneous exposure method using visible light. Higher performance is required for light sensitivity.

The present invention is to improve the problems of the conventional electrophotographic photoreceptor as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor having stable and good electrostatic characteristics and having a clear and high-quality image even when the environment at the time of forming a copy image fluctuates such as low temperature and low humidity or high temperature and high humidity. To provide.

Another object of the present invention is to provide a CPC electrophotographic photoreceptor having excellent electrostatic characteristics and low environmental dependency.

Another object of the present invention is to provide an electrophotographic photosensitive member effective for a scanning exposure method using a semiconductor laser beam.

Another object of the present invention is to provide an electrophotographic lithographic printing plate precursor having excellent electrostatic properties (particularly dark charge retention and light sensitivity),
By providing a lithographic printing original plate that reproduces a copy image that is faithful to the original image and that does not generate spotted background stains as well as uniform background stains on the printed material and that has excellent printing durability is there.

(Means for Solving the Problems) An object of the present invention is to provide an electrophotographic photosensitive member having a photoconductive layer containing at least an inorganic photoconductor and a binder resin, wherein the binder resin is represented by the following general formula (I). It contains at least one macromonomer having a weight average molecular weight of 1 × 10 ³ to 2 × 10 ⁴ as a polymerization component, and has a —PO ₃ H ₂ group and a —SO ₃ H group only at one end of the polymer main chain. , A -COOH group and ｛R ₁ is a hydrocarbon group or —OR ₂ (R ₂ is a hydrocarbon group)
An electrophotographic photoreceptor characterized in that it contains at least one type of graft copolymer (also referred to as resin [A]) comprising at least one acidic group selected from the group represented by the following formula: Is done.

General formula (I) In the formula (I), a ₁ and a ₂ may be the same or different from each other, and each is a hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group having 1 to 8 carbon atoms, —COO—Z, or Represents -COO-Z via a hydrocarbon group of 8 (Z represents a hydrocarbon group having 1 to 18 carbon atoms).

X represents -COO-, -OCO-, (L ₁ and l _{2 each} represent an integer of 1 to 3), (P ₁ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms), -CONHCONH-, -CONHCOO-, -O-, Or -SO ₂ - represent.

 Y represents a group linking X and -O-.

[] Represents a repeating unit, and n represents an integer of 1 to 3. When n is 2 or more, W in [] represents a group different from at least W in adjacent [].

W is Or CH _{2 4} (r ₁ and r ₂ may be the same or different and each represents a hydrogen atom or an alkyl group).

 R represents a hydrogen atom or a hydrocarbon group.

Further, the binder resin is 1 × 10 ^{3 of the} above resin [A].
A resin having a weight average molecular weight of about 2 × 10 ⁴ (hereinafter, this low molecular weight resin [A] may be particularly referred to as a resin [AL]) and the following resin [B];
The electrophotographic photosensitive member containing at least one resin selected from the group consisting of [C] and [D] further enhances the mechanical strength of the electrophotographic photosensitive member (when used as a printing plate, ) Is improved.

Resin [B] having a weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ , and —PO ₂ H
₂ group, -SO ₃ H group, -CO ₂ H groups and (R ₁ represents the same content as described above). A resin containing no group or basic group.

Resin [C]; having a weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ and 0.1 to 15 weight% of a copolymer component containing at least one functional group selected from an OH group and a basic group; % Containing resin.

Resin [D] having an average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ and containing an acidic group having a content of 50% or less of the acidic group contained in the resin [A] used in combination. P greater than the pKa of the acidic group contained in the resin or resin [A] contained as a copolymerization component
Having a Ka, -PO ₃ H ₂ group, -SO ₃ H groups, and -COOH groups (R ₃ represents a hydrocarbon group) A resin containing a copolymer component containing at least one kind of acidic group selected from groups.

The resin [A] used for the binder resin of the present invention is a graft copolymer containing a monofunctional macromonomer having a polyether structure represented by the general formula (I) as a copolymerization component. There, and the graft copolymer of the polymer main chain of the one terminal acidic group (-PO ₃ H ₂ group, -SO ₃ H group, -COO
H group and / or Resin.

The amount of the copolymer component in the polymer of the macromonomer of the general formula (I) and / or (II) is 1 to 100 parts by weight.
It is contained in a proportion of up to 70 parts by weight.

The amount of the acidic group bonded to the terminal of the main chain in the polymer is 0.5 to 10 parts by weight per 100 parts by weight.

The weight average molecular weight of the resin [A] is preferably 1 × 10 ^{3 to} 5 × 10 ^{5, and} more preferably, the polymer of the present invention has a low molecular weight of 1 × 10 ^{3 to} 1.5 × 10 ^4. The amount of the macromonomer is 40 to 70 parts by weight per 100 parts by weight, and the amount of the main chain terminal-bonded acidic group is 3 to 100 parts by weight.
It is better to increase with ~ 10 parts by weight. On the other hand, when the molecular weight of the polymer is as high as 7 × 10 ^{4 to} 5 × 10 ⁵ , the amount of the macromonomer is 1 to 40 parts by weight per 100 parts by weight, and The amount present is 0.1 to 100 parts by weight
Less is better with 2 parts by weight.

In the specification of the present application, the weight-average molecular weight (Mw) of the resin of the present invention is such that a polymer having a Mw of about 1,000 or more has good reproducibility as an experimental value.
The measurement values based on the "C method" are shown. Here, the resin containing the macromonomer of the present invention as a copolymer component differs from a linear polymer such as a random polymer in the presence state of its polymer chain in a solution, and has a specific form (for example, a polymer chain). Entanglement), the apparent molecular weight (Mw) may be small.

Conventionally known acidic group-containing binder resins as described above are mainly used for offset masters, and have a large molecular weight (for example, 5 × 10 ⁴ or more) in order to improve printing durability by maintaining film strength. Was a random copolymer, and the copolymer component containing an acidic group was randomly present in the polymer main chain.

In contrast, the binder resin [A] used in the present invention is:
The copolymer is a graft-type copolymer in which acidic groups contained in the resin are not randomly present in the polymer main chain but are specifically bonded only to the terminal of the main chain.

Therefore, the portion of the acidic group present at a specific position away from the main chain of the polymer is adsorbed on the stoichiometric defect of the inorganic photoconductor, and the main chain portion of the polymer is exposed on the surface of the photoconductor. It is presumed that the coating is loose and sufficient. As a result, it has been found that while compensating for the trap of the photoconductor and improving the humidity characteristics, the photoconductor is sufficiently dispersed and the aggregation is suppressed. That is, when the weight average molecular weight of the polymer is small, the coatability of the surface of the photoconductor is further improved, and in the case of the high molecular weight polymer, the photoconductor becomes remarkably remarkable in the case of a random copolymer. This is considered to be due to the fact that the phenomenon of promotion of aggregation between comrades is suppressed. Therefore, the smoothness of the surface of the photoconductive layer becomes smooth.

On the other hand, when a photoconductor having a rough surface of the photoconductive layer is used as the electrophotographic lithographic printing plate precursor, the dispersion state of the zinc oxide particles as the photoconductor and the binder resin is not appropriate, and an aggregate exists. Since the photoconductive layer is formed in the state, even if the desensitizing treatment with the desensitizing solution is performed, the non-image portion is not sufficiently and sufficiently hydrophilized, causing adhesion of the printing ink during printing, and as a result, The background stain on the non-image portion of the printed matter occurs.

On the other hand, in the case where the binder resin [A] according to the present invention is a low molecular weight substance, there was a concern that the film strength was weakened, but by sufficiently dispersing the photoconductor and adsorbing and coating it on the particle surface. It was found that the film properties were maintained and the film had sufficient film strength as a CPC photoreceptor or an offset master having thousands of printed sheets. Furthermore, it was found that the photosensitivity was better than that of a random copolymer resin containing an acidic group in the side chain linked to the polymer main chain.

Therefore, the spectral sensitizing dye usually used to maintain photosensitivity in the visible light to infrared light regions has a spectral sensitizing effect which sufficiently functions by adsorbing to the photoconductor. Is presumed to appropriately interact with the photoconductor without inhibiting the adsorption of the spectral sensitizing dye. This effect was particularly remarkable with cyanine dyes or phthalocyanine pigments, which are particularly effective as dyes for spectral sensitization of near infrared to infrared light.

If the molecular weight of the binder resin [A] is smaller than 10 ³ , the film-forming ability is reduced and sufficient film strength cannot be maintained. On the other hand, if the molecular weight is larger than 5 × 10 ⁵ , even if the resin of the present invention is used for electrophotography, The characteristics (especially, initial potential and dark decay retention) deteriorate, which is not preferable. In particular, in the case of such a high molecular weight substance, when the content of the acidic group exceeds 3% by weight, such deterioration of the electrophotographic characteristics is remarkable, and when used as an offset master, background stain becomes remarkable.

When the content of the acidic group bonded to the terminal of the main chain in the binder resin [A] is less than 0.5% by weight, the initial potential is low and a sufficient image density cannot be obtained. On the other hand, when the content of the acidic group is more than 10% by weight, the dispersibility decreases, the film smoothness and the high-humidity characteristics of the electrophotographic characteristics decrease, and the background stain increases when used as an offset master.

The glass transition point of the resin [A] is preferably in the range of -10C to 100C, more preferably -5C to 85C.

The macromonomer combined with the graft copolymer resin containing the macromonomer having a polyether structure of the present invention as a copolymer component will be described more specifically.

In the macromonomer of the general formula (I), preferably, a ₁ and a ₂ may be the same or different from each other, and each may be a hydrogen atom, a halogen atom (eg, a chlorine atom, a bromine atom,
A fluorine atom), a cyano group, an alkyl group having 1 to 3 carbon atoms (eg, a methyl group, an ethyl group, a propyl group, etc.), -COOZ
Or —CH ₂ COOZ (Z is an alkyl group having 1 to 8 carbon atoms (eg, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, etc.), and an aralkyl group having 7 to 9 carbon atoms) (For example, benzyl group, phenethyl group, 3-
Phenylpropyl group) or a phenyl group which may be substituted (for example, phenyl group, tolyl group, xylyl group, methoxyphenyl group, etc.).

More preferably, _one of a ₁ and a ₂ represents a hydrogen atom.

X is preferably -COO-, -OCO-, -CO-, -CH
_{2 COO-, CH 2 OCO -,} - CONH -, - CONHCONH -, - CONHCO
O- or Represents

P ₁ is a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, 2-methoxyethyl, 2-methoxyethyl) Chloroethyl group, 2-cyanoethyl group, benzyl group, methylbenzyl group, chlorobenzyl group, methoxybenzyl group, phenethyl group, phenyl group,
Tol, chlorophenyl, methoxyphenyl, butylphenyl, etc.).

Y represents a group linking X and -O-, and represents a group directly bonding or linking. Examples of Y representing a linking group include a divalent linking group which may be via a hetero atom (the hetero atom represents an oxygen atom, a sulfur atom, or a nitrogen atom). CH = CH, -O-, -S-, -COO -, - CONH -, - SO 2 -, - SO 2 NH -, - NHCOO-,
—A single or a combination of bonding units such as —NHCONH—. However, b ₁ and b ₂ may be the same or different and each represents a hydrogen atom, a halogen atom (eg, a chlorine atom, a bromine atom), a hydroxyl Group, cyano group, aliphatic group having 1 to 12 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, dodecyl group, benzyl group, phenethyl group, 2-chloroethyl Group,
2-cyanoethyl group, etc.), etc. represents, P ₂ represents the same content as the P _1}.

W is Or CH _{2 4} wherein r ₁ and r ₂ may be the same or different, and each represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms (eg, a methyl group,
Ethyl group, propyl group, butyl group, hexyl group, octyl group, etc.).

[] Represents a repeating unit, and n represents an integer of 1 to 3. However, when n is 2 or more, W in [] represents a group different from at least W in the adjacent [], and for example, the following combinations can be considered (in each of the following examples, w ₁ , w ₂ and w ₃ represent each a different group, the same meaning as W).

-XY-Ow ₁ -OR -XY-Ow ₁ -O] w ₂ -OR -XY-Ow ₁ -O] w ₂ -O] w ₃ -OR -XY-Ow _1- O] w ₂ -O] w ₁ -OR R represents a hydrogen atom or a hydrocarbon group. Examples of the hydrocarbon group include an alkyl group having 1 to 18 carbon atoms which may be substituted (for example, methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, dodecyl group,
Tetradecyl group, octadecyl group, 2-methoxyethyl group, 3-methoxyethyl group, 2-cyanoethyl group, 2-
An ethoxyethyl group or the like, an optionally substituted aralkyl group having 7 to 9 carbon atoms (for example, benzyl group, phenethyl group, 3
A phenylpropyl group, a methylbenzyl group, a dimethylbenzyl group, a methoxybenzyl group, a chlorobenzyl group, etc.), an alicyclic group having 5 to 8 carbon atoms (eg, a cyclopentyl group, a cyclohexyl group, etc.), and a substitution having 6 to 12 carbon atoms. Aromatic groups (eg, phenyl group, tolyl group, xylyl group, naphthyl group, chlorophenyl group, bromophenyl group, alkoxyphenyl group (alkyl groups such as methyl, ethyl, propyl, butyl, Hexyl group, octyl group, nonyl group, decyl group, dodecyl group, etc.), acetoxyphenyl group, methyl-chloro-phenyl group, propylphenyl group, butylphenyl group, decylphenyl group, etc.).

Of the macromonomer in the general formula (I) The following examples are given as specific examples of the portion represented by, but are not limited thereto. In the following respective examples, a is _{-H, -CH 3, -CH 2 COOCH} 3, -Cl, -
Br or represents -CN, b represents -H or -CH _3, l
Represents an integer of 1 or 2, m represents an integer of 2 to 12, and k represents an integer of 3 or 4.

The polyether type macromonomer represented by the general formula (I) can be produced by a conventionally known synthesis method. That is, it is obtained by a method of synthesizing by cationic polymerization of carboxylic acids or alcohols and epoxides or tetrahydrofurans. Specifically, PFRe
mpp and E. Fra-nta, Adv: Polym. Sci. 58 , 3 (1984), R. As
ami, M. Takaki, K. Kita and E. Asakura, Makromol. Chem. 18
6 , 685 (1985), R. Asami and M. Takaki, Makromol. Chem. S
uppl., 12 , 163 (1985), P. Rempp, P. Lutz, P. Massson and
Suppl. 8, 3 (1984), Takuzo Aida, Shohei Inoue, Journal of Organic Synthesis, 43 , 300 (1985), and the like.

Hereinafter, specific examples of the macromonomer represented by the general formula (I) to be used in the present invention are shown, but the scope of the present invention is not limited thereto. In each example, a, b, l, m, and k represent the same contents as described above.

The binder resin of the present invention is a graft copolymer containing the macromonomer of the general formula (I) as a copolymer component,
Any other copolymer component may be used as long as it satisfies the physical properties of the binder resin described above and can be radically copolymerized with the macromonomer.

Preferably, a monomer represented by the following general formula (II) is contained as a copolymer component in an amount of 30% by weight to 99% by weight in the copolymer.

General formula (II) In the general formula (II), b ₁ and b ₂ represent a ₁ and a ₂ in the formula (I).
Represents the same content as described above, and more preferably represents a hydrogen atom or a methyl group.

X ₁ is -COO -, - OCO- or represents -O-, preferably a -COO-.

R ₀ represents a hydrocarbon group having 1 to 18 carbon atoms. Preferably, an alkyl group having 1 to 18 carbon atoms which may be substituted (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group,
Dodecyl group, tridecyl group, tetradecyl group, 2-methoxyethyl group, 2-ethoxyethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, 2-hydroxypropyl group, 2-chloroethyl group, 2-cyanoethyl group, 2 -(N, N-dimethylamino) ethyl group, 2,3-dihydroxypropyl group, 3-canivamoylpropyl group, etc., an optionally substituted aralkyl group having 7 to 12 carbon atoms (for example, benzyl group, phenethyl group) , Methoxybenzyl, ethoxybenzyl, methylbenzyl, dimethylbenzyl, chlorobenzyl, dichlorobenzyl, dibromobenzyl, acetoxybenzyl, cyanobenzyl, naphthylmethyl, 2-naphthylethyl, etc.), carbon An optionally substituted cycloalkyl group of the formulas 5 to 8 (for example, cyclopentene) Group, cyclohexyl group, cycloheptyl group, etc.), an optionally substituted aryl group (e.g., phenyl group, tolyl group, xylyl group,
Mesityl, naphthyl, methoxyphenyl, ethoxyphenyl, chlorophenyl, dichlorophenyl, bromophenyl, dibromophenyl, chlorobromophenyl, acetoxyphenyl, acetylphenyl, chloro-methyl-phenyl, bromo- Methyl-phenyl group, cyanophenyl group, methoxycarbonylphenyl group, etc.).

Further, the resin of the present invention may contain other monomers as copolymer components together with the macromonomer of the general formula (I) and the monomer of the general formula (II).

For example, α-olefins, vinyl alkanoate or allyl esters, acrylonitrile, methacrylonitrile, vinyl ethers, acrylamides, methacrylamides, styrenes, heterocyclic vinyls (for example, vinylpyrrolidone, vinylpyridine, vinylimidazole,
Vinyl thiophene, vinyl imidazoline, vinyl pyrazole, vinyl dioxane, vinyl quinoline, vinyl thiazole, vinyl oxazine, etc.).

However, these other monomers do not exceed 20% by weight or more in the copolymer.

In the graft copolymer of the present invention, when the amount of the copolymer component corresponding to the macromonomer is 1% by weight or less, the dispersion as the coating material for the photosensitive layer cannot be sufficiently performed. If it exceeds 70% by weight, the copolymerization with the general formula (II) does not proceed sufficiently, and the polymerization of the monomer of the general formula (II) or other monomers other than the desired graft copolymer is not sufficient. Coalescence forms. Furthermore, when these resins are dispersed, aggregation with the photoconductor occurs.

Resin (A) of these graft copolymers the main chain terminal acidic group (-PO ₃ H ₂ groups, -SO ₃ H group, -COOH group, Is a resin to which is bonded. Here, the hydrocarbon group represented by R ₁ and R ₂ has the same content as the hydrocarbon group represented by R in formula (I). As a method for producing these resins, specifically, a method using a polymerization initiator containing a functional group capable of being converted into the acidic group or later and replacing the acidic group, or a method using the acidic group or later the acidic group A method using a chain transfer agent containing a functional group that can be converted into a compound, a method using both of them, and a method using a termination reaction in an anionic polymerization method to introduce the functional group can be used. it can.

For example, P. Dreyfuss, RPQuirk, Encycl, Polym. Sci. En
g. 7, 551 (1987), V. Percec, Appl. Polym. Sci. 285, 95 (1
985), PFRempp, E. Franta, Adv. Polym. Sci. 58 , 1 (198
4), Y.Yamashita, J.Appl.Polym.Sci.Appl.Polym.Symp.
36 , 193 (1981), R. Asami, M. Takaki, Makromol. Chem. Sup
pl. 12 , 163 (1985) and the like.

In the electrophotographic photoreceptor of the present invention, higher mechanical strength may be desired while maintaining its excellent electrophotographic properties. For this purpose, a method of introducing a heat and / or photocurable functional group into the main chain of the graft copolymer can be applied.

That is, in the present invention, a monomer containing at least one heat and / or photocurable functional group is copolymerized with the macromonomer of the formula (I) and preferably the monomer represented by the general formula (II). It is preferable to contain as. The heat and / or photocurable functional group appropriately crosslinks the polymers, thereby strengthening the interaction between the polymers and improving the strength as a film. Therefore, the resin of the present invention further containing such a heat and / or photo-curable functional group can prevent the interaction between the binder resin and the appropriate adsorption / coating of the surface of the zinc oxide particles and the binder resin. It has the effect of strengthening the film and, as a result, improving the film strength.

The heat and / or light curable functional group of the present invention refers to a functional group capable of curing a resin by at least one of heat and light.

The “thermosetting functional group (functional group that performs a thermosetting reaction)” in the present invention includes, for example, Tsuyoshi Endo “Refinement of thermosetting polymer”
(CMC Co., Ltd., 1986), Yuji Harasaki, "The latest binder technology handbook" Chapter II-I (General Technology Center, 1985), Takayuki Otsu, "Synthesis, design and new application development of acrylic resin" (Chubu Management Development) Center Publishing Department, 1985), Eizo Omori "Functional Acrylic Resin" (Techno System, 1985)
The functional groups described in the references can be used in reviews such as annual publications.

For example -OH group, -SH group, -NH ₂ group, -NHR ₁₁ group (R ₁₁ represents a hydrocarbon group, specifically the same meaning as R ₀ in the formula (II)), -CONHCH ₂ OR ₁₂ (R ₁₂ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms (for example, a methyl group, an ethyl group, a propyl group,
Butyl group, hexyl group, octyl group, etc.) -N = C = O group or {Wherein g ₁ and g ₂ each represent a hydrogen atom, a halogen atom (eg, a chlorine atom, a bromine atom, etc.) or an alkyl group having 1 to 4 carbon atoms (eg, a methyl group, an ethyl group, etc.)}, and the like. . As the polymerizable double bond group, specifically, CH ₂ CHCH—, CH ₂ CHCH—CH ₂ —, _{CH 2 = CH-NHCO-, CH} 2 = CH-CH 2 -NHCO-, CH 2 = CH-
SO _2- , CH ₂ = CH-CO-, CH ₂ = CH-O-, CH ₂ = CH-S
-, And the like.

Examples of the “photo-curable functional group” of the present invention include, for example, Takahiro Tsunoda, “Photosensitive Resin”, Printing Society Publishing Division (1972), Mototaro Nagamatsu, Hideo Inui, “Photosensitive Polymer” Kodansha (1977) G .
A. Delgenne, “Encyclepedia of Polyemer Science and
Technology, Supplemant. "Vol 1 (1976), etc. Specific examples include addition polymer groups such as allyl ester groups and vinyl ester groups, cinnamoyl groups, and optionally substituted maleimides. And a dimerization group such as a ring group.

In the present invention, in order to synthesize a resin containing a heat and / or photocurable functional group, the heat and / or photocurable functional group is used as a copolymer component containing the heat and / or photocurable functional group. A monomer containing a group may be used.

When the resin of the present invention contains the thermosetting functional group, a reaction accelerator may be added, if necessary, to promote a crosslinking reaction in the photosensitive layer film. In the case of a reaction mode for forming a chemical bond between functional groups, for example, an organic acid (acetic acid, propionic acid, butyric acid, benzenesulfonic acid, p-toluenesulfonic acid and the like), a cross-linking agent and the like can be mentioned.

Specific examples of the cross-linking agent include compounds described in Shinzo Yamashita and Tosuke Kaneko, “Cross-Linking Agent Handbook”, Taiseisha (1981) and the like. For example, commonly used crosslinking agents such as organic silane, polyurethane, and polyisocyanate, and curing agents such as epoxy resin and melamine resin can be used.

In the case of the polymerization reaction mode, a polymerization initiator (peroxide,
Azobis-based compounds and the like, preferably azobis-based polymerization initiators), and monomers having a polyfunctional polymerizable group (for example, vinyl methacrylate, allyl methacrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, divinyl succinate) Acid esters, divinyl adipates, diallylsuccinates, 2-methylvinyl methacrylate, divinylbenzene, etc.).

In the present invention, when a binder resin containing such a thermosetting functional group is used, a thermosetting treatment is performed.
This thermosetting treatment can be performed by strictly setting the drying conditions at the time of the conventional photoreceptor production. For example, 60 ℃ ~ 12
The treatment may be performed at 0 ° C. for 5 minutes to 120 minutes. When the above-described reaction accelerator is used in combination, the treatment can be performed under milder conditions.

In the present invention, the binder resin further comprises a resin having a low molecular weight (resin [AL] having a weight average molecular weight of 1 × 10 ³ to 2 × 10 ⁴ ) and the aforementioned high molecular weight (weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ ). Resin [B],
When any one of [C] and [D] is contained, the mechanical strength of the electrophotographic photosensitive member is further improved.

The resins [B] to [D] sufficiently increase the mechanical strength of the photoconductive layer, which is insufficient with the resin [A] alone.

In addition, low molecular weight resin [AL] and high molecular weight resin [B]
The electrophotographic photoreceptor of the present invention, which is used in combination with any one of (A) to (D), has good photoconductive layer surface smoothness even when used as an electrophotographic lithographic printing plate precursor, and is a photoconductor. Since certain zinc oxide particles are sufficiently dispersed in the binder, if desensitization treatment is performed with a desensitization treatment solution, the non-image area becomes evenly and sufficiently hydrophilized. Adhesion to the image area is suppressed, and even when printing a large number of prints such as 10,000, no background stain is generated.

That is, in the present invention, the resin [AL] and the resin [B] to
When used in combination with any one of [D], the interaction between the adsorption and coating of the inorganic photoconductor and the binder resin is appropriately performed,
In addition, the film strength of the photoconductive layer is more favorably maintained.

In the resin [AL], the amount of the macromonomer (formula (I)) in the copolymer is 40 to 70% by weight based on 100 parts by weight of the resin [AL]. The weight average molecular weight of the resin [AL] is preferably 1 × 10 ^{3 to} 1.5 × 10 ⁴ , more preferably ³ × 10 ^{3 to} 1.5 × 10 ⁴ .
× 10 ^{3 to} 1.0 × 10 ⁴ .

In the binder resin used in the present invention, the case where the low-molecular-weight resin [AL] and the high-molecular-weight resin [B] containing no acidic group or basic group at all are used in combination.

The resin [B] that can be used in the present invention does not contain the above-described acidic group (main-chain terminal acidic group contained in the resin [A]) in any of the polymer main chain and the terminal, and also contains a basic group. No resin having a weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ . More preferably, the weight average molecular weight is from 8 × 10 ^{4 to} 3 × 10 ⁵ .

The glass transition point of the resin [B] is preferably 0 ° C to 120 ° C.
And more preferably from 10 ° C to 80 ° C.

As the resin [B], any resin conventionally used as a binder resin for electrophotography may be used, and it may be used alone or in combination. For example, Harumiya Miyahara,
Reference materials such as Hidehiko Takei, "Imaging", 1978 No. 89-12, Ryuji Kurita, Jiro Ishiwatari, "Polymer", 17,278-284 (1968), etc.

Specifically, olefin polymers and copolymers, vinyl chloride copolymers, vinylidene chloride copolymers, vinyl alkanoate polymers and copolymers, allyl alkanoate polymers and copolymers, styrene and its derivatives, Polymers and copolymers, butadiene-styrene copolymer, isoprene-styrene copolymer, butadiene-unsaturated carboxylic acid ester copolymer, acrylonitrile copolymer, methacrylonitrile copolymer, alkyl vinyl ether copolymer, Acrylic acid ester polymer and copolymer, methacrylic acid ester polymer and copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, itaconic acid diester polymer and copolymer, maleic anhydride Acid copolymer, acrylamide copolymer, methacrylamide copolymer, water Group modified silicone resins, polycarbonate resins, ketone resins, amide resins, hydroxy- and carboxy-modified polyester resins, butyral resins,
Polyvinyl acetal resin, cyclized rubber-methacrylate copolymer, cyclized rubber-acrylate copolymer, copolymer containing a nitrogen-free heterocycle (for example, furan ring, tetrahydrofuran as a heterocycle) Ring, thiophene ring, dioxane ring, dioxolane ring, lactone ring, benzofuran ring, benzothiophene ring, 1,3
—Dioxetane ring etc.) epoxy resin and the like.

More specifically, a (meth) acrylic copolymer or polymer containing at least one monomer represented by the following general formula (III) as a (co) polymer component in a total amount of 30% by weight or more: The union can be mentioned as an example of the resin [B].

General formula (III) In the formula (IV), d ₃ represents a hydrogen atom, a halogen atom (for example, a chloro atom or a bromo atom), a cyano group, or a carbon atom having 1 to 4 carbon atoms.
And preferably an alkyl group having 1 to 4 carbon atoms. R ′ is an alkyl group having 1 to 18 carbon atoms which may be substituted (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tridecyl group, A tetradecyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, etc., an optionally substituted alkenyl group having 2 to 18 carbon atoms (for example, vinyl group, allyl group, isopropenyl group, butenyl group, hexenyl group, heptenyl) Group, octenyl group, etc.), an optionally substituted aralkyl group having 7 to 14 carbon atoms (eg, benzyl group, phenethyl group, methoxybenzyl group, ethoxybenzyl group, methylbenzyl group, etc.), substitution having 5 to 8 carbon atoms. A cycloalkyl group (eg, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, etc.), an aryl group (eg, Group, tolyl group, xylyl group, mesityl group, naphthyl group, methoxyphenyl group, ethoxyphenyl group, chlorophenyl group,
Dichlorophenyl group). R ′ is preferably an alkyl group having 1 to 4 carbon atoms, an aralkyl group having 7 to 14 carbon atoms which may be substituted (particularly preferably, a benzyl group, a phenethyl group, a naphthylmethyl group which may be substituted as an aralkyl group, 2-naphthylethyl group) or a phenethyl group or naphthyl group which may be substituted (as a substituent, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a propyl group, an acetyl group, a methoxycarbonyl group, Ethoxycarbonyl group and the like, and these substituents may be substituted by 2 to 3).

Further, the component copolymerized with the (meth) acrylate in the resin [B] may be a monomer other than the general formula (III), for example, α-olefins, vinyl alkanoate or Allyl esters, acrylonitrile, methacrylonitrile, vinyl ethers, acrylamides, methacrylamides, styrenes, heterocyclic vinyls [for example, containing 1 to 3 nonmetal atoms other than nitrogen atoms (oxygen atoms, sulfur atoms, etc.) 5- to 7-membered heterocyclic ring, and specific compounds include vinylthiophene, vinyldioxane, and vinylfuran. Preferred examples include, for example, vinyl or allyl esters having 1 to 3 carbon atoms, acrylonitrile, methacrylonitrile, styrene and styrene derivatives (for example, vinyltoluene, butylstyrene, methoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene). , Ethoxystyrene, etc.).

On the other hand, examples of the basic group not contained in the resin [B] that can be used in the present invention include an amino group which may have a substituent and a nitrogen atom-containing heterocyclic group.

Next, in the binder resin used in the present invention, the low-molecular-weight resin [AL] described above is combined with a high-molecular-weight resin [C] containing at least one of an OH group and a basic group. Will be described in detail.

In the resin [C], the proportion of the copolymer component containing an -OH group and / or a basic group is 0.05 to 15% by weight, more preferably 0.5 to 10% by weight in the resin [C]. .
The weight average molecular weight of the resin [C] is 5 × 10 ^{4 to} 5 × 10 ⁵ , preferably 8 × 10 ⁴ to 10 ⁵ . The glass transition point of the resin [C] is preferably in the range of 0 ° C to 120 ° C, more preferably 10 ° C to 80 ° C.

In the present invention, the OH group component or the basic group component in the resin [C] has a weak interaction with the photoconductor particle interface and the resin [AL], and stabilizes the dispersion of the photoconductor dispersion. In addition, it is considered to have an effect of further improving the film strength after forming the film. However, when the proportion of these components in the resin [C] exceeds 15% by weight, the composition is affected by moisture, and the moisture resistance of the photoconductive layer is reduced.

As the resin [C], a conventionally known resin as described in the resin [B] can be used as long as it has the above-mentioned physical properties.

More specifically, an example of the resin [C] is a (meth) acrylic copolymer containing a monomer represented by the aforementioned general formula (III) as a copolymer component in a total amount of 30% by weight or more. Can be mentioned.

The “copolymerization component containing an OH group and / or a basic group” contained in the resin [C] includes the above-mentioned substituent (OH group and / or basic group) copolymerizable with the aforementioned general formula (III). Any group can be used as long as it is a vinyl compound containing a group. Examples of the basic group include an amino group represented by the following general formula (IV) and a nitrogen-containing heterocyclic group.

General formula (IV) In the formula (IV), R ₁₃ and R ₁₄ may be the same or different and each is a hydrogen atom, an alkyl group which may be substituted (eg, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl Group, decyl group, dodecyl group, tetradecyl group, octadecyl group, 2-bromoethyl group, 2-chloroethyl group, 2-hydroxyethyl group, 2-cyanoethyl group, 2-methoxyethyl group, 3-ethoxypropyl group, etc.), substitution Alkenyl groups (e.g., allyl group, isopropenyl group, 4-butynyl group, etc.), aralkyl groups which may be substituted (e.g., benzyl group, phenethyl group, chlorobenzyl group, methylbenzyl group, methoxybenzyl group, Hydroxybenzyl group), alicyclic group (eg, cyclopentyl group, cyclohexyl group, etc.), aryl group (eg, phenyl group) , A tolyl group, a xylyl group, a mesityl group, a butylphenyl group, a methoxyphenyl group, a chlorophenyl group, etc.). Further, R ₁₃ and R ₁₄ may be linked by a hydrocarbon group which may be via a hetero atom.

Further, as the nitrogen-containing heterocyclic ring, the nitrogen atom is 1 to
Heterocycles consisting of a 5- to 7-membered ring containing three rings may be mentioned, and these heterocycles may further be formed by forming a condensed ring with a benzene ring, a naphthalene ring or the like. Further, these rings may contain a substituent. Specifically, for example, a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a piperazine ring, a pyrimidine ring, a pyridazine ring, an indolizine ring, an indole ring, a 2H-pyrrole ring, a 3H-indole ring, an indazole ring, a purine ring, Morpholine ring,
Isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxazine ring, acridine ring, phenanthridine ring, phenazine ring, pyrrolidine ring, pyrroline ring, imidazolidine ring, imidazoline ring, pyrazolidine ring, pyrazoline ring,
Piperidine ring, piperazine ring, quinacridine ring, indoline ring, 3,3-dimethylindolenine ring, 3,3-dimethylnaphthoindolenine ring, thiazole ring, benzothiazole ring, naphthothiazole ring, oxazole ring, benzoxazole ring, naphtho Oxazole ring, selenazole ring, benzoselenazole ring, naphthoselenazole ring, oxazoline ring, isoxazole ring, benzoxazole ring, morpholine ring, pyrrolidone ring, triazole ring,
Examples include a benzotriazole ring and a triazine ring.

These OH groups and / or basic groups are described in, for example, “Polymer Data Handbook [Basic Edition]” edited by The Society of Polymer Science, Baifukan (1986) and the like. By including in the substituent of the ester derivative or amide derivative derived from
The desired monomer is obtained. For example, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 3-hydroxy-2-chloromethacrylate,
Hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 10-hydroxydecyl methacrylate, N- (2-hydroxyethyl) acrylamide,
N- (3-hydroxypropyl) methacrylamide, N
-(Α, α-dihydroxymethyl) ethyl methacrylamide, N- (4-hydroxybutyl) methacrylamide, N, N-dimethylaminoethyl methacrylate, 2-
(N, N-diethylaminoethyl) methacrylate, 3-
(N, N-dimethylpropyl) methacrylate, 2- (N, N
-Dimethylethyl) methacrylamide, hydroxystyrene, hydroxymethylstyrene, N, N-dimethylaminomethylstyrene, N, N-diethylaminomethylstyrene, N-butyl-N-methylaminomethylstyrene, N
And various monomers such as-(hydroxyphenyl) methacrylamide. Examples of the vinyl compound having a nitrogen-containing heterocyclic ring include the aforementioned “Polymer Data Handbook (Basic Edition)”, pp. 175-181, DATomalia,
"Reactive Heteracyclic Monomers" chap 1 of "Funct
ional Monomers Vol.2 ", Marcel DeRRer Icn.NY (197
4), LSLusRin "Basic Monomers" chap 3 of "Functi
onal Monomers Vol.2 ", MarcelDeRRer Inc.NY (197
4) and the like.

Further, the resin [C] may contain other monomers as copolymer components in addition to the above-mentioned monomer containing an OH group and / or a basic group. For example, the same monomers as those described as being contained as another copolymer component in the resin [B] can be mentioned as specific examples.

Next, in the binder resin used in the present invention, the low-molecular-weight resin [AL] and an acid having a content of 50% or less, preferably 30% or less of the content of acidic groups contained in the resin [AL]. In combination with a high molecular weight resin (D) containing a group as a side chain of the copolymer component, or a side chain of the copolymer component having an acid group having a larger pKa than the acidic group contained in the resin (AL). The case of use will be described in detail.

The resin [D] has a weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ , preferably 7 × 10 ⁴ to 4 × 10 ⁵ .

The acidic group contained in the polymer side chain of the resin [D] is preferably contained in the resin [D] at a ratio of 0.05 to 3% by weight. More preferably, it is 0.1 to 1.5% by weight. Further, it is preferable to include an acidic group in the resin [D] in the combination shown in Table A below.

The glass transition point of the resin [D] is preferably 0 ° C to 120 ° C.
, More preferably 0 ° C to 100 ° C. More preferably, it is 10 ° C to 80 ° C.

Resin [D] has a very weak interaction with photoconductor particles as compared to resin [AL], and has a function of covering gently, without alienating the function of resin [AL] at all.
The resin [AL] alone sufficiently increases the mechanical strength of the photoconductive layer, which is insufficient.

Further, the content of the acidic group in the side chain in the resin [D] is 3% by weight.
Is exceeded, adsorption of the resin [D] to the photoconductor particles occurs,
The dispersion of the photoconductor is destroyed, and agglomerates or precipitates are formed, so that the coating cannot be formed, or even if the coating is formed, the obtained photoconductor has an electrostatic property of It is not preferable because the surface is remarkably lowered, and the surface of the photoreceptor is roughened to deteriorate the mechanical abrasion resistance.

In resin [D] R ₃ is more specifically an optionally substituted alkyl group having 1 to 12 carbon atoms (eg, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group, a dodecyl Group, 2-chloroethyl group, 2-
A methoxyethyl group, a 2-ethoxyethyl group, a 3-methoxypropyl group and the like, an optionally substituted aralkyl group having 7 to 12 carbon atoms (for example, benzyl group, phenethyl group, chlorobenzyl group, methoxybenzyl group, methylbenzyl) Group or the like), an optionally substituted alicyclic group having 5 to 8 carbon atoms (such as a cyclopentyl group or a cyclohexyl group) or an optionally substituted aryl group (such as a phenyl group,
Tolyl, xylyl, mesityl, naphthyl, chlorophenyl, methoxyphenyl, etc.).

The resin [D] may be any of the conventionally known resins as long as it has the above-mentioned physical properties. For example, the conventionally known resin described in the resin [B] can be used.

More specifically, an example of the resin [D] is a (meth) acrylic copolymer containing a monomer represented by the above general formula (III) as a copolymer component in a total amount of 30% by weight or more. Can be mentioned.

The “copolymer component containing an acidic group” in the resin [D] used in the present invention is, for example, any vinyl compound containing an acidic group that can be copolymerized with the general formula (III). Can be used. For example, “Polymer Data Handbook (Basic Edition)” edited by The Society of Polymer Science, Baifukan (19
86). Specifically, acrylic acid,
α- and / or β-substituted acrylic acid (for example, α-acetoxy form, α-acetoxymethyl form, α- (2-amino) methyl form, α-chloro form, α-bromo form, α-fluoro form, α
-Tributylsilyl form, α-cyano form, β-chloro form,
β-bromo form, α-chloro-β-methoxy form, α, β-
Dichloro compound), methacrylic acid, itaconic acid, itaconic acid half esters, itaconic acid semiamides, crotonic acid,
2-alkenyl carboxylic acids (eg, 2-pentenoic acid,
2-methyl-2-hexenoic acid, 2-octenoic acid, 4-methyl-2-hexenoic acid, 4-ethyl-2-octenoic acid, etc.), maleic acid, maleic acid half esters, maleic acid half amides, vinyl Benzenecarboxylic acid, vinylbenzenesulfonic acid, vinylsulfonic acid, vinylphosphonic acid,
Examples include a half ester derivative of a vinyl group or an allyl group of a dicarboxylic acid, and an ester derivative of a carboxylic acid or a sulfonic acid, or a compound containing the acidic group in a substituent of an amide derivative.

The following are specific examples of these compounds. However, in each of the following examples, e is -H,-
_{CH 3, -Cl, -Br, -CN} -, - CH 2 COOCH 3 or -CH ₂ COOH
Are shown, f is indicated -H or -CH _3, n ₁ represents an integer of 2 to 18, m ₁ represents an integer of 1 to 12, l ₁ represents an integer of 1-4.

Further, the resin [D] of the present invention contains, in addition to the monomer of the above general formula (III) and the monomer containing an acidic group, other monomers other than these as copolymer components. Is also good. For example, the same monomers as those described as being contained as another copolymer component in the resin [B] can be mentioned as specific examples.

Further, the resin [AL] and the resin [C] or [D] of the present invention.
In addition, other resins can be used in combination. Examples of such resins include alkyd resins, polybutyral resins, polyolefins, ethylene-acid copolymers, styrene resins, styrene-butadiene resins, acrylate butadiene resins, and vinyl alkanoate resins.

If the above other resin exceeds 30% (weight ratio) of the total binder resin [AL] and [C] or [D] using the resin of the present invention, the effect of the present invention (particularly, improvement of electrostatic characteristics) ) Is lost.

The ratio of the amount of the resin [AL] used in the present invention and any one of the resins [B] to [D] varies depending on the type, particle size, and surface state of the inorganic photoconductive material used. The ratio of [AL] and any of the resins [B] to [D] used is 5 to 80 to 95 to 20 (weight ratio), preferably 15 to 80.
It is 60 to 85 to 40 (weight ratio).

The ratio of the weight average molecular weight of any of the resin [AL] and the resin [B] to [D] is preferably 1.2 or more, more preferably
2.0 or higher.

Examples of the inorganic photoconductive material used in the present invention include zinc oxide, titanium oxide, zinc sulfide, cadmium sulfide, cadmium carbonate, zinc selenide, cadmium selenide, tellurium selenide, and lead sulfide.

The total amount of the binder resin used for the inorganic photoconductive material is 10 to 100 parts by weight, preferably 15 to 50 parts by weight, based on 100 parts by weight of the photoconductor.

In the present invention, various dyes can be used as spectral sensitizers as needed. For example, Harumiya Miyamoto, Hidehiko Takei, "Imaging", 1973 (No.8), page 12, CJ Young
RCA Review 15, 469 (1954), Kohei Kiyota, IEICE Transactions J63C (No.2) , 97 (1980), Yuji Harasaki, etc., Industrial Chemistry Magazines 66 78 and 188 (1963), Tadaaki Tani, Carbonium dyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, phthalein dyes, polymethine dyes (for example, oxonol dyes, merocyanine dyes, etc.) described in the review articles of the Photographic Society of Japan 35 , 208 (1972), etc.
Cyanine dye, rhodacyanine dye, styryl dye, etc.),
And a phthalocyanine dye (which may contain a metal).

More specifically, those using mainly carbonium dyes, triphenylmethane dyes, xanthene dyes, and phthalein dyes are described in JP-B-51-452,
-90334, JP-A-50-114227, JP-A-53-39130,
JP-A-53-82353, U.S. Pat. No. 3,052,540, U.S. Pat. No. 4,054,450, and JP-A-57-16456 are examples.

Oxonol dyes, merocyanine dyes, cyanine dyes, polymethine dyes such as rhodacyanine dyes, F.
M. Hamer `` The Cyanine Dyes and Related Compounds ''
Can be used, more specifically, more specifically,
U.S. Patent 3,047,384, U.S. Patent 3,110,591, U.S. Patent 3,121,008, U.S. Patent 3,125,447, U.S. Patent 3,128,179, U.S. Patent 3,132,942, U.S. Pat.
622,317, UK Patent 1,226,892, UK Patent 1,309,
No. 274, British Patent No. 1,405,898, JP-B-48-7814, JP-B-55-18892 and the like.

Further, as polymethine dyes for spectrally sensitizing the near infrared to infrared light region having a long wavelength of 700 nm or more, JP-A-47-840, JP-A-47-44180, JP-B-51-41061, and JP-A-51-41061 49−5034
No., JP-A-49-45122, JP-A-57-46245, JP-A-56
No. -35141, JP-A-57-157254, JP-A-61-26044,
JP-A-61-27551, U.S. Pat.No. 3,619,154, U.S. Pat.No.4,175,956, `` Research Disclosure '' 1982, 21
6, pages 117 to 118 and the like. The photoreceptor of the present invention is excellent in that even when various sensitizing dyes are used in combination, the performance is hardly changed by the sensitizing dye. Furthermore, various conventionally known additives for an electrophotographic photosensitive layer such as a chemical sensitizer can be used in combination, if necessary.
For example, the review mentioned above: Imaging 1973 (No. 8) No. 12
"Recent development and commercialization of photoconductive materials and photoreceptors", e.g., electron accepting compounds (e.g., halogen, benzoquinone, chloranil, acid anhydride, organic carboxylic acid, etc.) and Hiroshi Komon, which are described in pages and other reviews. Chapters 4 to 6 include polyarylalkane compounds, hindered phenol compounds, P-phenylenediamine compounds, and the like, which are reviewed in Japanese Science Information Co., Ltd., Publishing Division (1986).

The amounts of these various additives are not particularly limited, but are usually 0.0001 to 2.0 parts by weight based on 100 parts by weight of the photoconductor.

The thickness of the photoconductive layer is preferably from 1 to 100 µ, particularly preferably from 10 to 50 µ.

When a photoconductive layer is used as the charge generation layer of the photoreceptor in which the charge generation layer and the charge transport layer are stacked, the thickness of the charge generation layer is preferably 0.01 to 1 μm, particularly preferably 0.05 to 0.5 μm.

In some cases, an insulating layer is provided for the main purpose of protecting the photoreceptor, improving durability, and improving dark attenuation characteristics. At this time, the insulating layer is set relatively thin, and the insulating layer provided when the photosensitive member is used in a specific electrophotographic process is set relatively thick.

In the latter case, the thickness of the insulating layer is between 5 and 70 μm, especially 10
Set to ~ 50μ.

Examples of the charge transport material of the laminated photoreceptor include polyvinyl carbazole, oxazole dyes, pyrazoline dyes, and triphenylmethane dyes. The thickness of the charge transport layer is preferably 5 to 40 μm, particularly preferably 10 to 30 μm.

As the resin used for forming the insulating layer or the charge transport layer, typical ones are polystyrene resin, polyester resin, cellulose resin, polyether resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride-copolymer resin, A thermoplastic resin of a polyacryl resin, a polyolefin resin, a urethane resin, an epoxy resin, a melamine resin, a silicone resin, and a curable resin are appropriately used.

The photoconductive layer according to the present invention can be provided on a conventionally known support. Generally, the support of the electrophotographic photosensitive layer is preferably conductive. As the conductive support, a base material such as a metal, paper, or a plastic sheet is impregnated with a low-resistance substance in the same manner as in the related art. A substrate that has been subjected to a conductive treatment, for example, by applying a conductivity to the back surface of the substrate (the surface opposite to the surface on which the photosensitive layer is provided), and further coated with at least one layer for the purpose of preventing curling and the like. A substrate provided with a water-resistant adhesive layer on its surface, a substrate provided with at least one or more precoat layers as necessary on the surface layer of the support, or a substrate conductive plastic on which Al or the like is deposited is laminated on paper. Can be used.

Specifically, as examples of the conductive substrate or the conductive material, Yukio Sakamoto, “Electrophotography”, 14 (No. 1), P2-11 (19)
75), Hiroyuki Moriga, "Introduction to Special Paper Chemistry", Polymer Publishing Association (1975), MFHoover, J. Macromol. Sci. Chem. A-4.
(6), and those described in pages 1327 to 1417 (1970) and the like are used.

(Examples) Examples of the present invention will be described below, but the contents of the present invention are not limited thereto.

Synthesis Example 1: Resin [A] of the Present Invention 1: (A-1) 60 g of benzyl methacrylate, 20 of methyl acrylate
g, a mixture of 20 g of a macromonomer (MM-1) having the following structure and 200 g of toluene were heated to a temperature of 70 ° C. under a nitrogen stream.
4,4'-azobis (4-cyanovaleric acid) (abbreviated as ACV) 1.
0 g was added and the mixture was stirred for 4 hours. Further, 0.4 g of ACV was added, and 2 hours, and then 0.2 g of AIV was further added, followed by stirring for 3 hours. The weight average molecular weight (abbreviation: ▲ ▼) of the obtained copolymer was 4.5.
× 10 ⁴

Synthesis Examples 2 to 7 of Resin [A] of the Present Invention: (A-2) to (A-
7) In Synthesis Example 1 of resin [A], the macromonomer (MM
-1) was replaced with the macromonomer shown in Table 1 below,
By reacting in the same manner as in Synthesis Example 1, resins [A] in Table 1 below were synthesized. ▲ ▼ of the obtained copolymer is 4 × 10
It was ^{4 ~5.5} × 10 ^4.

Synthesis Example 8 of Resin [A] of the Present Invention: A-8 A mixed solution of 60 g of benzyl methacrylate, 40 g of a macromonomer (MM-8) having the following structure, 150 g of toluene and 50 g of isopropyl alcohol was heated to 80 ° C. under a nitrogen stream. Warmed.

ACV5.0g was added and stirred for 4 hours. Further, 1.0 g of ACV was added, and after 2 hours, 0.5 g of ACV was added, followed by stirring for 3 hours.

The weight average molecular weight of the obtained copolymer was 8.3 × 10 ³ .

Synthesis Example 9 of Resin [A] of the Present Invention: (A-9) A mixed solution of 50 g of benzyl methacrylate, 50 g of macromonomer (MM-9) having the following structure, 4.0 g of thioglycolic acid and 200 g of toluene was placed under a nitrogen stream. Heated to a temperature of 75 ° C. 2,2'-azobisisobutyronitrile (abbreviation: AIB
N.) 1.5 g was added and stirred for 4 hours, further 0.4 g of AIBN was added for 2 hours, and then 0.2 g of AIBN was further added and stirred for 3 hours. The weight average molecular weight of the obtained copolymer was 7.0 × 10 ³ .

Example 1 and Comparative Example A 40 g (as solid content) of resin (A-1) of Synthesis Example 1 of resin, 200 g of zinc oxide, cyanine dye [I] having the following structure:
A mixture of 018 g, 0.10 g of phthalic anhydride and 300 g of toluene was dispersed in a ball mill for 2 hours to prepare a photosensitive layer-forming product, which was then subjected to conductive treatment on paper so that the dry adhesion amount was 200 g / m ² . Then, the resultant was applied with a wire bar, dried at 110 ° C. for 30 seconds, and then left in a dark place at 20 ° C. and 65% RH for 24 hours to produce an electrophotographic photosensitive material.

Comparative Example A The resin used as a binder resin in Example 1 (A-
Instead of 1), only 40g of resin (P-1) having the following structure
An electrophotographic photosensitive material was produced in the same manner as in Example 1 except that the electrophotographic photosensitive material was used.

The film properties (surface smoothness), film strength, electrostatic properties, imaging properties of these photosensitive materials and the imaging properties when the environmental conditions were set to 30 ° C. and 80% RH were examined. Further, when these photosensitive materials are used as an offset master, the photoconductive desensitizing property (expressed by the contact angle of the photoconductive layer with water after the desensitizing treatment) and printability (ground stain, Printing durability).

 The above results are summarized in Table-2.

The embodiments of the evaluation items shown in Table 2 are as follows.

Note 1) Smoothness of photoconductive layer: The obtained photosensitive material was measured for its smoothness (sec / cc) using a Beck smoothness tester (manufactured by Kumagaya Riko Co., Ltd.) under the condition of an air capacity of 1 cc. It was measured.

Note 2) Mechanical strength of photoconductive layer: The surface of the obtained photosensitive material was emery paper (#) with a load of 50 g / cm ² using a Haydon-14 type surface test material (manufactured by Shinto Chemical Co., Ltd.). Abrasion powder was removed 1000 times repeatedly at 1000) to remove the abrasion powder, and the remaining film ratio (%) was determined from the weight loss of the photosensitive layer to determine the mechanical strength.

Note 3): Electrostatic properties: Paper analyzer (Kawaguchi Electric Co., Ltd. paper analyzer) in a dark room at a temperature of 20 ° C. and 65% RH.
After the 20 seconds corona discharge -6kV with SP-428 type), allowed to stand for 10 seconds to measure the surface potential V ₁₀ at this time.
Then, the potential V ₁₈₀ after standing for 180 seconds in the dark was measured, and the potential retention after dark decay for 180 seconds, that is,
Dark decay retention rate [DRR (%) of _{(V 180 / V 10) ×} 100 (%) ]
I asked for it.

After charging the surface of the photoconductive layer to −400 V by corona discharge, the surface is irradiated with monochromatic light having a wavelength of 780 nm, and the surface potential (V ₁₀ ) is reduced.
The time required to decay to 1/10 is determined, and the exposure E
Calculate _1/10 (erg / cm ² ).

Note 4) Imageability: Each photosensitive material was allowed to stand for one day and night under the following environmental conditions. Next, charged at -5 KV, using a gallium-aluminum-arsenic output of 2.8 mW as a light source and a semiconductor laser (oscillation wavelength of 780 nm), at a radiation dose of 64 erg / cm ² on the surface of the photosensitive material, at a pitch of 25 μm and a scanning speed. Visual evaluation of the copied image (fog, image quality) obtained by developing and fixing using ELP-T (manufactured by Fuji Photo Film Co., Ltd.) as a liquid developer after exposure at a speed of 300 m / sec. did.

Environmental conditions at the time of imaging were 20 ° C 65% RH and 30 ° C 80% RH.

Note 5) Contact angle with water: Each photosensitive material was treated with a desensitizing solution ELP-EX (manufactured by Fuji Photo Film Co., Ltd.) using an etching processor.
After passing through the surface to desensitize the surface of the photoconductive layer, a drop of 2 μm of distilled water is placed thereon, and the contact angle with the formed water is measured with a goniometer.

Note 6) Printing durability Each of the photosensitive materials is subjected to plate making under the same conditions as in Note 4) to form a toner image, and is subjected to desensitization under the same conditions as in Note 5) above. Indicates the number of sheets that can be printed on an offset printing machine (Oliver 52, manufactured by Sakurai Seisakusho Co., Ltd.) without causing background contamination in the non-image area of the printed matter and no problem with the image quality of the image area. Is good).

Note 7): Dm (image density) Indicates the maximum value of the solid toner image density (measurable by Macbeth reflection densitometer).

As shown in Table 2, the photosensitive material of the present invention and Comparative Example A had good photoconductive layer smoothness and electrostatic properties, and the actual copied image had no ground fogging and the copied image quality was clear. This is presumed to be due to the fact that the photoconductor and the binder resin were properly adsorbed and covered the particle surface, and did not hinder the adsorption of the spectral sensitizing dye.

For the same reason, even when used as an offset master master, the desensitizing treatment with the desensitizing solution proceeds sufficiently, and the contact angle with water in the non-image area is 15 ° or less and sufficiently hydrophilized. ing. Even when the printed matter was actually printed and the background stain was observed, no stain was observed.

However, in the case of Comparative Example A, although the film strength was sufficient, the electrostatic characteristics, particularly the DRR, were significantly reduced, and a sufficient copied image could not be obtained even when actually imaged. E
_The apparent decrease of _1/10 was due to a decrease in DRR, which was different from the fact that the so-called photoconductivity, which produces conductivity by light irradiation, was good. This means that in the conventional resin, which is a random copolymer, the surface of the oxidized sub-particles is excessively and strongly coated, and the adsorption of the dye on the particle surface is inhibited, thereby deteriorating the electrostatic characteristics. ,
It is presumed to indicate that the zinc oxide etching does not proceed sufficiently even after the desensitization treatment.

As described above, the photosensitive material of the present invention was favorable in all aspects of the smoothness, film strength, electrostatic properties and printability of the photoconductive layer.

Examples 2 to 7 In Example 1, instead of 40 g of the resin (A-1),
Each resin (A-A) produced in Synthesis Examples 2 to 7 of the resin [A]
Each of the photosensitive materials was manufactured in the same manner as in Example 1 except that 40 g of 2) to (A-7) were used. In the same manner as in Example 1, the smoothness, film strength, and electrostatic characteristics of each photosensitive material were measured, and the results are shown in Table 3.

The photosensitive materials of the present invention are excellent in chargeability, dark charge retention rate, and light sensitivity. A clear image without any occurrence was given. Further, when printed as an offset master plate, it was possible to print 7000 sheets or more of clear images without background fog in non-image areas.

Example 8 In Example 1, instead of 40 g of the resin (A-1),
8 g of resin (A-8) (as solid content) and poly (ethyl methacrylate) (weight average molecular weight 3.4 × 10 ⁵ ) [resin (B
1) An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 32 g was used. The characteristics of the obtained photoreceptor were measured in the same manner as in Example 1.

The surface of the photoconductive layer had a smoothness of 98 (sec / cc). V ₁₀ : -580 V, DRR: 86%, E _1/10 27 (erg / cm ² ), and good image quality was obtained even at (30 ° C., 80% RH).

The light-sensitive material of the present invention is excellent in chargeability, dark charge retention rate, and light sensitivity, and the occurrence of ground fogging and fine line skipping even under severe conditions of high temperature and high humidity (30 ° C., 80% RH) in actual copied images. Gave a clear image without any etc. Further, when printed as an offset master master, 10,000 or more printed matters having clear images without background fogging in non-image areas could be printed.

Example 9 In Example 8, 8 g of resin (A-3) was used instead of 8 g of resin (A-8), and poly (butyl methacrylate) (weight average molecular weight 3.4 × 10 ⁵ ) was used instead of resin (B-1). ) [Resin (B-2)] An electrophotographic photosensitive member was prepared in the same manner as in Example 8, except that 32 g of Resin (B-2) was used.

When the respective characteristics were measured in the same manner as in Example 1, the smoothness of the photoconductive layer surface of each photoconductor was 100 (sec / cc) and smooth. _{V 10; -570V, DRR; 87} %, an ^{_{E 1/10 29 (erg / cm 2}} ), was a good image quality in imaging properties at (30 ℃, RH 80%) . Further, 10,000 sheets or more could be printed even when printed as an offset master master.

Examples 10 to 15 The same procedures as in Synthesis Example 9 except that in Synthesis Example 9 of the resin [A] of the present invention, 4 g each of a mercapto compound (chain transfer agent) shown in Table 4 was used instead of 4 g of thioglycolic acid. Similarly, each resin [A] was produced.

Each of these copolymers was used in place of 8 g of the resin (A-8) and processed under the same conditions as in Example 8 to prepare each photosensitive material.

All of the photoreceptors of the present invention exhibited excellent characteristics. or,
When printing was performed as an offset master plate, 10,000 or more printed materials were obtained.

Examples 16 to 25 (Synthesis of Resin A-16) 2,6-dichlorophenyl methacrylate 60 g, macromonomer (MM-9) 40 g, thioglycolic acid 2 g, toluene 1
A mixture of 50 g and ethanol 50 g under a nitrogen stream at a temperature of 80 ° C.
Was heated. 3 g of ACV was added and reacted for 4 hours.
0 g was added and reacted for 4 hours. The weight average molecular weight of the obtained copolymer was 8.5 × 10 ³ .

(Preparation of photoconductor) 9 g (as solid content) of the above resin (A-16)
In a ball mill, a mixture of 31 g of the resin [C] represented by No. 5, 0.02 g of the heptamethine cyanine dye [II] represented by the following structural formula, 0.15 g of phthalic anhydride and 300 g of toluene was added.
The dispersion was dispersed over time to prepare a photosensitive layer formed product. The following operations were performed in the same manner as in Example 1 to produce an electrophotographic photosensitive member.

The electrostatic characteristics of these photosensitive materials were measured using a paper analyzer in the same manner as in Example 1. However, a gallium-aluminum-arsenic semiconductor laser (oscillation wavelength: 830 nm) was used as a light source. The results are shown in Table-6.

Examples 26 to 37 6 g of a resin (A-17) having the following structure, 34 g of the resin [D] in Table 7 below, 0.018 g of the cyanine dye [I], 0.15 g of maleic anhydride, 200 g of zinc oxide and toluene 300 g of the mixture was dispersed in a ball mill for 2 hours to prepare a photosensitive layer-formed product. Hereinafter, an electrophotographic photosensitive member was produced in the same manner as in Example 1.

All photosensitive materials of the present invention are chargeable, dark charge retention,
Excellent light sensitivity, real copy image is high temperature and humidity (30 ℃, 80%
Even under severe conditions (RH), a clear image was obtained without occurrence of ground fogging or fine line skipping.

Further, a printed matter of clear image quality free from background stain was obtained regardless of whether the offset master was printed or 10,000 sheets were printed after plate making in the same manner as in Example 1.

Examples 38 to 43 and Comparative Example B 7.5 g of resin (A-18) having the following structure, 32.5 g of each of resins [B] to [D] shown in Table 8 below, 200 g of zinc oxide, 0.0 g of uranine
2g, Rose Bengal 0.04g, Bromphenol Blue 0.0
A mixture of 3 g, 0.20 g of phthalic anhydride and 300 g of toluene was dispersed in a ball mill for 2 hours to prepare a photosensitive layer-formed product, which was then wire-coated on a paper treated with a conductive material so that the dry adhesion amount became 22 g / m ^2. Coated with a bar and dried at 110 ° C. for 1 minute. Next, each electrophotographic photoreceptor was prepared by being left in a dark place at 20 ° C. and 65% RH for 24 hours.

Comparative Example B In Example 38, the resin (P) was used as a binder resin in place of 7.5 g of the binder resin (A-18) and 32.5 g of the resin [B].
-1) An electrophotographic photoreceptor was prepared in the same manner as in Example 38 except that 40 g was used.

Note 8) Electrostatic characteristics: A paper analyzer (Kawaguchi Electric Co., Ltd. paper analyzer) in a dark room at a temperature of 20 ° C. and 65% RH.
After the 20 seconds corona discharge 6kV with SP-428 type), allowed to stand for 10 seconds to measure the surface potential V ₁₀ at this time.
Then, the potential V ₇₀ after standing still in the dark for 60 seconds was measured, and the retention of the potential after dark decay for 60 seconds, that is, the dark decay retention rate [DRR (%)] was calculated as (V ₇₀ / V ₁₀ ) x 100 (%)
I asked for it. Also, the surface of the photoconductive layer is -400 V by corona discharge.
After charged, the photoconductive layer surface is irradiated with visible light illumination 2.0 lux, it obtains the time until the surface potential (V ₁₀₎ is attenuated to 1/10, now exposure E _1/10 (lux・
Second).

Here, the offset original plate for printing was made under the following conditions.

After leaving each photosensitive material for one day and night under the following environmental conditions, E was used with a fully automatic plate making machine ELP-404V (manufactured by Fuji Photo Film Co., Ltd.).
A copy image (fog, image quality) obtained by making a plate using LP-T as a toner was visually evaluated. Environmental conditions at the time of imaging were 20 ° C. and 65% RH (I) and 30 ° C. and 80% RH (II).

Each photoreceptor of the present invention and Comparative Example B are examples in which the spectral sensitizing dye is replaced with three dyes that sensitize in the visible light region. In the case of the dyes used here, the electrophotographic properties were satisfactory even in Comparative Example B in which a conventional random copolymer was used as the binder resin. In addition, the desensitizing treatment of the non-image area was not sufficient, and background stains were generated from printing.

In each photosensitive material of the present invention, such a phenomenon was not observed, and 80
More than 00 prints with clear image quality and no background fog were obtained.

(Effects of the Invention) According to the present invention, an electrophotographic photosensitive member having excellent electrostatic characteristics and mechanical strength can be obtained.

Claims (4)

(57) [Claims] 1. An electrophotographic photoreceptor having a photoconductive layer containing at least an inorganic photoconductor and a binder resin, wherein the binder resin has a weight average molecular weight of 1 × 10 ³ represented by the following general formula (I). ２2 × 10 ⁴ macromonomers are contained as a polymerization component, and only at one end of the polymer main chain are —PO ₃ H ₂ groups, —SO ₃ H groups, —COOH groups and ｛R ₁ is a hydrocarbon group or —OR ₂ (R ₂ is a hydrocarbon group)
An electrophotographic photoreceptor comprising at least one graft copolymer (resin [A]) formed by bonding at least one acidic group selected from group (1). General formula (I) In the formula (I), a ₁ and a ₂ may be the same or different from each other and each represent a hydrogen atom, a halogen atom, a cyano group,
Represents a hydrocarbon group having 1 to 8 carbon atoms, -COO-Z or -COO-Z via a hydrocarbon group having 1 to 8 carbon atoms (Z represents a hydrocarbon group having 1 to 18 carbon atoms). X represents -COO-, -OCO-, (L ₁ and l _{2 each} represent an integer of 1 to 3), -CO-, (P ₁ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms), -CONHCONH-, -CONHCOO-, -O-, Or -SO ₂ - represent a. Y represents a group linking X and -O-. [] Represents a repeating unit, and n represents an integer of 1 to 3. When n is 2 or more, W in [] represents a group different from at least W in adjacent []. W is Or CH _{2 4} (r ₁ and r ₂ may be the same or different and each represents a hydrogen atom or an alkyl group) R represents a hydrogen atom or a hydrocarbon group. 2. The resin [A] has a weight average molecular weight of 1 × 10 ³ to 2 × 10 ⁴ , and the binder resin further comprises the following resin [B]:
3. The electrophotographic photoreceptor according to claim 1, further comprising: Resin [B] having a weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ , and —PO ₃ H
₂ group, -SO ₃ H group, -CO ₂ H groups and ｛R ₁ represents the same content as described above) and a resin containing no basic group. 3. The resin [A] has a weight average molecular weight of 1 × 10 ³ to 2 × 10 ⁴ , and the binder resin further comprises the following resin [C]:
3. The electrophotographic photoreceptor according to claim 1, further comprising: Resin [C]; having a weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ and 0.1 to 15 weight% of a copolymer component containing at least one functional group selected from an OH group and a basic group; % Containing resin. 4. The resin [A] has a weight average molecular weight of 1 × 10 ³ to 2 × 10 ⁴ , and the binder resin further comprises the following resin [D]:
3. The electrophotographic photoreceptor according to claim 1, further comprising: Resin [D] having a weight average molecular weight of 5 × 10 ^{4 to} 5 × 10 ⁵ and containing an acidic group having a content of 50% or less of the acidic group contained in the resin [A] used in combination. has a pKa greater than pKa of the acid groups contained in the resin or resin (a) containing a copolymer component, -PO ₃ H ₂ group, -SO ₃ H groups, and -COOH groups (R ₃ represents a hydrocarbon group) A resin containing a copolymer component containing at least one kind of acidic group selected from groups.